| 摘要 |
1418663 Making heat exchangers; jointing UNITED KINGDOM ATOMIC ENERGY AUTHORITY 26 March 1973 [27 March 1972] 14288/72 Headings B3A and B3V [Also in Division C1] A refractory artefact having a predetermined internal structure is made by adhering a plurality of components composed of refractory material in powder form and a binder, at least one of the components having apertures to define the structure when they are adhered, and subsequently heat treating the adhered components. The refractory material may be glass, e.g. petalite or a borosilicate or lithium aluminosilicate glass, porcelain, lithium alumino-silicate, alumina, zirconia, tungsten carbide or silicon carbide, a metal such as nickel or stainless steel or silicon. In the example, Fig. 1, green sheets of silicon are formed into a heat exchanger, Fig. 2 (not shown), for a Sterling engine the silicon being converted into silicon nitride during heat treatment. A layer formed from a slurry of silicon powder, polyvinyl butyral, dibutyl phthalate and methyl ethyl ketone was deposited on a carrier, dried, removed from the carrier, edge trimmed and sixteen of the layers were rolled down to give a composite sheet <SP>1</SP>/ 16 inch thick. Apertures were then punched to form sheets 1-4 which are painted with ethanol and stacked under a weight whilst the ethanol evaporated. The assembly, including a refractory tube 5, was then heated to 200‹ C. in air and held at this temperature for ten hours, followed by heating to 400-500‹ C. in air. Heat treatment in a nitriding furnace followed; the Specification includes a temperature-time schedule for the heat treatment. Instead of ethanol, toluene may be used. |
